1. Field of the Invention
The present invention relates to an elastic coupling device provided with elastic members capable of damping the variation of driving force of, for example, a diesel engine. More specifically, the present invention relates to a compression elastic coupling device for transmitting power by compressing elastic members interposed between input and output shafts.
2. Description of the Related Art
Conventional compression elastic coupling devices include a device A disclosed in, for example, JP-A No. 27142/1995. The device A is a dual torsional elastic coupling device provided with low-rigidity elastic members having a low torsional rigidity and arranged near the center, and high-rigidity elastic member shaving a high torsional rigidity and arranged near the periphery. Power is transmitted from a drive flange through the low-rigidity elastic members to a driven member when torque is low. Power is transmitted from the drive flange through both the low-rigidity and the high-rigidity elastic members to the driven member when load is large.
Other conventional devices B, C and D are mentioned in the specifications and drawings of German Patent Nos. 2624500, 29716165 and 3432436, respectively. Those conventional devices A, B, C and D have the following drawbacks that need improvement.
Device A: Since both the low-rigidity and the high-rigidity elastic members of the device A are not held fixedly, play of the input and the output shaft relative to each other is liable to occur due to the plastic shrinkage of the elastic members due to aging. Since the elastic members are arranged axially in a space between the drive side and the driven side, a large open space is necessary to move axially a machine on the drive side and a machine on the driven side relative to each other in order to incorporate the elastic members into the device A or replacing the elastic members. Inspection of the device A requires troublesome work and the device A is difficult to be maintained. Since the elastic members are not cooled, the elastic members are susceptible to fatigue deterioration.
Devices B and C: Elastic members interposed between an input shaft (drive shaft) and an output shaft (driven shaft) are not mechanically fixed. Therefore it is possible that play of the input shaft and the output shaft relative to each other occurs due to the plastic shrinkage of the elastic members due to aging, noise is generated by the play, and the input shaft exerts a shock load on the output shaft. The devices B and C are heavy. The elastic members cannot easily be inspected for deterioration due to aging. Since the elastic members are arranged axially in a space between the input and the output shaft, a large open space is necessary to move axially a machine on the side of the input shaft and a machine on the side of the output shaft relative to each other in order to incorporate the elastic members into the devices B and C or replacing the elastic members. Inspection of the devices B and C takes time and the devices B and C are difficult to be maintained. Since the elastic members are not cooled, the elastic members are susceptible to fatigue deterioration.
Device D: Although the direction of arrangement of elastic members between input and output shafts is not mentioned in the specification, it is inferred from the drawings that the elastic members are axially arranged. Therefore, as mentioned in connection with the devices A, B and C, a machine on the side of the input shaft and a machine on the output shaft must axially be moved relative to each other to form a large open space in replacing the elastic members. Inspection of the device D takes time and the device D is difficult to be maintained. Since the device D is not provided with any cooling mechanism for cooling the elastic members, the elastic members are susceptible to fatigue deterioration.